Does not really matter what wording they will put in. It is clear that project will go to pay or get nothing way. So just start working on decommissioning it. Free software really need better ways to pay developers, that will allow to avoid crap like that.

I would add LVM to the list of software raids, and remove btrfs as poorly engineered.

couple of old 2.5 HDD + usb to SATA converter. But Pi5 is hardly suitable to host anything. May just get old PC (which gives you HDD too). There are plenty for < $100 or even free. But you are going to pay more for power.

I do not see why it will cause any problems with exception of stacking mapping layer. I wonder can LVM do it natively without adding intermediate block device of 2 x 2G?

ROCm on RX 570? RLY?

Stay with TP-Link. Ubiquity done some strange things recently.

Many sells, some just wipe them, some just contains encrypted data. If you happy with just used drive eBay is full of surprises.

Some diagram would help. Are you trying to use your server as a switch?

Why create yourself a headache and still get substandard and no-warranty drive. If you want cheaper drives go for reconditioned/refurbished/used drives. Same risks, better product. Old enterprise SAS drives are cheap and many still have plenty of heath in them.

Do you plan to compress video ( which generally already compressed format) when saving to remote location? I do not see use case for it, as you ether use lossless compression and not compressing it in any meaningful way, or just re-encode to different format and loose quality. Second option is simpler to achieve by re-encoding before sending out.

Yes, it will. Will it make any difference for you, depends of what are you doing. I would not use surveillance drive in to server, they are way too specific. Outside of that prices is pretty much same per TB/(Warranty Year) accross the board.

I done some excessive research couple of years back on the topic. you can find it here https://blog.holms.place/2022/05/01/hdd-storage-cost-comparation-may-2022.html. I do not think situation have changed match since than. Price per TB/Year is nearly constant past 8GB size.

Also consider looking to re-certified drives, or even refurbished drives. you may save hips on them. But it depends on how much you value your data, how much redundancy in you storage pool and how good your backup strategy.

Syncthing sync files, it is all does.

Look to other orchestrations solution too, like SALT. If you need to manage a lot of servers it is live saver. Setting up is only first step.

Usually just plug/unplug couple of times is enough. No fancy chemicals.

Run long smart test on the disk and check smart data after that. Other possibility is ZFS pool is nearly full.

Depends what are you doing. Something like keep base os patched is pretty much nil efforts. Some apps more problematic than others. Home Assistant is always a pain to upgrade and something like postfix is requires nearly 0 maintenance.

circular dependency seems to be the case. I guess adding second external resolver to /etc/resolve.conf will help. Second entry will not be used unless first one ( pi-hole) is responding. But it need to be tested.
BTW, why do you want to send host’s DNS via pihole?

what exactly do you mena under subdomains? Any DNS provider will support adding NS entries for subdomains if you want to host you sub-zone somwhere, And any should allow you to use names with “.” in it for “fake” subzone, like
a.subzone1 IN A x.x.x.x
a.subzone2 IN A y.y.y.y

nope, it is very deeply customized debian. Need to be installed from scratch.

Open source projects need to make money somehow. I found VyOS method quite acceptable. They giving good instruction and tools to build your own stable ISO. So do not be lazy or contribute somehow. Unfortunately their paid support costs too much. I was considering trying to push VyOS to be used as virtual router at my work, but it costs more than Cisco C8000v